Automatic telephone system



June 22, 1943. H. P. BoswAu 2,322,219

AUTOMATIC TELEPHONE SYSTEM Filed Dec. 21, 1940 4 Sheets-Sheet l Fig. 1Q

June 22, 1943. H. P. BOSWAU 2,

AUTOMATIC TELEPHONE SYSTEM Filed D60.-21, 1940 4Sheets-Sheet 3 June 22, 1943. H. P. BOSWAU AUTOMATIC TELEPHONE sYsTm.

Filed Dec. 21, 1940 4 Sheets-Sheet 4 Patented June 22, 1943 UNITED STATES PATENT OFFICE AUTOMATIC T lii lii lzolva SYSTEM I Original application November 30, 1939, Serial No. 306,929. Divided and this application December 21, 1940. Serial No. 371.065

33 Claims.

on which Patent No. 2,307,757 was granted Jan.

The invention and various features provement comprised therein will be described hereinafter in connection with the accompanying drawings, in which:

Fig. l is a partial side view of a single unit of switching equipment;

Fig. 2 is a section on the line 2--2, Fig. 1, drawn to a somewhat larger scale;

Fig. 3 is a top view of the switching unit shown in Figs. 1 and 2, with certain parts bro-- ken away;

Figs. 4 to 7, inclusive, are views which show details of the supporting means for certain of the operating bars; 1 bezig. 8 shows one of the link operating mem- Flg. 9 is a fragmentary view of a switching unit in perspective, intended to facilitate an understanding of the principles on which it operates; and

V Fig. 10 is an exploded view of a part of the bank, showing the-construction of the contact members and insulators.

, Referring now to Figs. 1 to 10, inclusive, the switching which is shown in these views will be described.

The various parts of the unit are mounted on a frame which comprises vertical end members I and 2, of angle iron, and top and bottom members3 and 4. The top member 3 is a flat metal plate ha in upturned end 5, Fig. 1, which is secured to the member i by screws, asshown. The opposite end is similarly up- 1 turned and is secured to the verticalmember 2.

' The member 3 is also provided with upturned side flanges 6 and 'l. The bottom member 4 is similar to member 3 and is provided with downturned ends II and II which are secured to the vertical members. I and 2, respectively. The

bottom member 4 also has downturned flanges ,l and along the sides. Thus a rigid frame is provided upon which all theswitching unit are mounted.

The contact bank comprises ten parallel sections extending transversely of the switching unit and supported between the top and bottom plates 3 and 4. There is also a special section at one endof the unit, provided for a purpose which will be described subsequently. The complete bank consists in partof elements individual to each section and in part of common elements, the latter comprising rigid flat conducting bars extending lengthwise of the switching unit through all the sections inseries.

The contact bank may be explained more in detail in connection with Figs. 1 and 10. Considering the first regular bank section, there is a rectangular strip of insulation l4 which extends transversely across the bottom plate 4, and on this strip l4 there is placed a similar strip l5. Resting on the latter strip is a strip of conducting material It, which has a series of eleven contact springs, such as II, II, It,

and ill, Fig. 10. formed integrally therewith. The complete strip It with its integrally formed contact springs may be punched from a sheet of suitable material. Each of the insulating strips, such as l4 and It may have an opening at each end, surrounded by a raised rim on the top of the strip, which is adapted to fit in an opening in a" strip such as I. and a corresponding depression in the bottom of the next insulating strip'above. This is a customary expedient used to assist in aligning the bank elements.

Above the conducting strip I there is asvsenlbled an insulating strip II, which is similar to l4 except that its upper surface is pro- .vided with a plurality of notches for receiving the contact element 22 and a serlesof ten conducting bars, such as 24, 23 and 23. The element 22 is provided with a terminal lug 33 which extends outside the bank There are nine other bank sections to the right of the first section which are identical with the first section. Fig. 1 shows the second section and part of the third, and also shows a special section at the left of the first regular section. In each of these sections the first fixed 4 1 contact element at the edge of the bank is a contact element such as 23 which is individual to the section. In the special section and in the second section, Fig. 1, these contact elements are indicated at II and '3. respectively. The

remaining fixed contact elements onthis layer comprise the ten flat conducting bars, suchas parts of the 24, 25, and 26, which extend through and are common to all the sections. These bars extend beyond the tenth section at the right hand end of the unit, and the projecting ends of the bars i'orm terminals for the attachment of conductors.

The second layer of the bank is similar to the first, and in the case of the first regular section comprises the insulating strip 21, the conducting strip 23 having eleven integrally formed contact springs, such as 35, 3B, 31, and 38, and notched insulating strip 28, the fixed contact element 33 provided with lug 3|, and ten fiat conducting bars, such as 32, 33, and 34, the latter being common to all the sections, like bars 24, 25, and of the first level.

The third layer of the bank is also similar to the first layer, and comprises in the case of the first regular section the insulating strip 39, the conducting strip having eleven contact springs such as 48 formed integrally therewith. the notched insulating strip 4|, the fixed contact element 42 having lug 43, and ten flat conducting bars, such as 44, 45, and 46. These bars are common to all the sections.

The conducting bars 44, 32, and 24 constitute a three-conductor line or trunk, bars 44 and 32 being the line bars while bar 24 is the test bar; that is, the two line conductors of a subscriber's line or of a trunk line may be connected to bars 44 and 32, while the test conductor is connected to bar 24. Thus it will be seen that the thirty bars in the first three layers of the bank represent ten three-conductor lines or trunks which are common to all sections of the bank. The three conducting strips 40, 28. and ii of the first regular section are the three conductors of an intermediate trunk or link circuit which extends across or in coordinate relation to the ten lines or trunks represented by the ten sets of bars, such as 44, 32, 24, etc. Since the other nine regular sections of the bank are similar to the first section, there are in the first three layers of the bank ten of these intermediate link circuits each of which intersects each of the line or trunk circuits. Any link circuit can be connected to any line or trunk circuit by operation of the contact springs at the point of intersection. For example, the link circuit in the first regular section can be connected to the first line or trunk circuit by pressing contact springs 55, 36, and

i3 into engagement, respectively, with bars 44,

32, and.24.

There are twenty-seven additional layers in .the bank above the first three layers which have been described, making thirty layers altogether. The additional layers may be considered as comprising nine sets'oi three layers each. In each set of three layers there are thirty bars corresponding to bars such as 44, 32, and 24, representing ten three-conductor lines or trunks. Also in each set oi three layers there are thirty conducting strips, such as 40, 28, and I3, three to each of the regular bank sections, and constituting ten three-conductor link.circuits. In the complete switching unit there are, therefore, three hundred oi the fiat conducting bars, such as 44, 32, and 24, representing one hundred three-conductor lines or trunks. There are also three hundred of the transverse conducting strips, such as 43, 23, and I5, arranged thirty to each regular bank section. Each such bank section, therefore, contains ten link circuits and, since there are ten regular bank sections, the total number of link circuits is one hundred.

The method by which the bank is built up may follow known practice in assembling such structures. It may be built up layer by layer on the bottom plate 4, as suggested in the previous description, and before the top plate 3 is assembled in the frame, suitable jigs being used for assisting in keeping the different sections in place as they are being assembled. When all the elements are in place the top plate 3 may be placed in position and pressure can be applied to compress the bank, after which the top plate 3 can be secured to the end members I and 2. To give additional security, rods such as 55, Fig, 1, may be provided, passing up through the'bottom plate 4 and through the openings, such as 49 and so, in the bank elements and threaded into the top plate 3. There may be one of these rods at each end of each bank section.

As previously mentioned, the line or trunk bars, such as 44, 32, and 24, extend to the right beyond the tenth regular bank section, and the ends of the bars are formed into terminal lugs for the attachment of wires or cable conductors. In Fig. 3 the ends of the top layer of bars can be seen, the end of top plate 3 being broken away. There are twenty-nine similar layers beneath the one shown.

As seen from the sectional view, Fig. 2, the three hundred line or trunk bars form ten vertical rows or groups of thirty bars each. The first group includes bars 24, 32, 44, and twentysevenother bars in the same vertical row, the second group comprises jbars 25, 33, 45, and twenty-seven other bars in the same vertical row, and so on. The numbering of the lines or trunks in each group may be from the top down. The first three bars in the first vertical row may be assigned to the first line or trunk, the next three to the second, and so on, bars 44, 32, and 24 being assigned to the'tenth or 0 line or trunk of the group.

As previously mentioned, there are in each of the ten regular bank sections, ten intermediate link circuits, each comprising three conducting strips, such as 40, 28, and I6, which constitute the lowermost or tenth lin'k circuit in the first regular section. This link circuit may be regarded as terminating in the three contact springs 48, 35, and I1, and each of the nine link circuits above terminates in a similar set of contact springs. Associated with the contact springs 43, 35, and I1 there is a set of fixed contacts comprising contacts 42, 30 and 22, provided with lugs 43, 3|, and 23, and each of the other sets of contact springs has associated with it a similar set of fixed contacts. The several sets of fixed contacts in the first regular section are all connected in multiple by strapping at the terminal lugs; that is, lugs 43, 3i, and 23 are connected, respectively, to the three corresponding lugs of the contact set immediately above, and the latter three lugs are connected, respectively, to the next three lugs above, and. so on. The ten contact sets of the first section thus strapped together constitute the multiple terminals of a trunk line, to which any link circuit of the first section may be connected by pressing its terminal contact springs, such as 48, 35, and I1, into engagement with their associated fixed contacts, such as 42, 30, and 22.

Each of the nine other regular bank sections is wired Just as described in the case of the first regular section, and there are, therefore, ten trunk lines which terminate in multiple connected contact sets in the ten regular bank secframe plate 4 by means of screws.

tions, respectively. These trunk linesmay be outgoing trunk or incoming trunks, depending on the switching stage at which the unit is used.

'Ihe special bank section which is'shown to the left of the first regular section in Fig. 1 may be the same as the regular sections insofar as the contact elements contained therein are concerned. However, the function of this special bank does not involve the closing of any circuits to the line conductors, and hence the conducting strips which correspond to strips, such as 43 and 23, may be omitted, as indicated in the drawing. Plain metal strips having no contact springs and functioning as spacers may be inserted instead. The first, fourth, seventh, etc. layers are equipped with conducting strips such as 51, having contact springs, such as 53 and 54. At each of these strips the first contact spring such as 53 is bent up and soldered to the individual contact element such as 5| above. The ten lugs, such as 53 and 53, therefore, can be used as terminals for the ten conducting strips such as 51. The conducting strip 61 terminating at lug 56 and having ten contact springs such as 54 constitutes means for extending a connection to the testconductor of any one of the ten lines or trunks of the bottom layer in the bank, and the other similar conducting strips above have the same functions with respect to the lines or trunks in the corresponding layers of the bank.

The mechanism for operating the contact springs of the bank will now be explained, with reference particularly to Fig. 2, which shows a section taken just to the right of the first regular bank section as seen in Fig. 1. Considering the first vertical row of bars, such as 44, 32, and 24, with their associated contact springs, such as 66, 36, and I3, the latter are operated by means of a vertical longitudinally movable operating bar having a plurality of projections thereon equal to the number of contact springs in the vertical row, or thirtyaltogether. This operating bar comprises a rod 63 on which there is molded a cylindrical body 6I of insulating material having projections, such as 62, 63, and 64. There are ten of these operating bars assigned to the first bank section, as seen in Fig. 2.

The ten operating bars above referred to are provided with bearings which are supported on the top and bottom plates 3 and 4. The top, plate is slotted at 61, Fig. 4, and the bottom plate at 33, Fig. 5, to permit the operating bars to be inserted after the bank has been assembled. The bars are, of course, inserted in such a manner that the projections 62, 63, etc. are not interfered with by the bars 44, 32, etc., and are then rotated 90 to the positions in which they are shown. The upper bearing is formed by a notched strip 63 and a strip 13 having a single long recess in one side thereof, these strips being assembled from opposite sides of the row of bars 63 and being secured to the frame plate 3 by means of two screws. As can be seen from Fig. 6, the bars 63 lie in the notches 1| of strip l It will be clear that the described arrangement prevents rotation of the rods 63.

The contact springs, such as I3, 36, and 55 are tensioned lightly against the projections, such as 62-, 63, and 64. The projections 63, 64, etc. rest on the bars 24, 32-, etc., which support the weight of the bar 63-3I. Each bar is slidable vertically to close simultaneously all the contacts in the associated vertical row. When bar 63 is raised vertically, for instance, all of the thirty contact springs, such as I3 and 36, are pressed irto engagement with the corresponding bars 24, 3 etc. a

Each of the ten regular bank sections is, of course, provided with a set of ten vertical operating bars similar tothose described in thecase of the first section. There are, therefore, one hundred of these operating bars.

The mechanism for raising the operating bars will next be described. To accomplish this purpose there is provided at each regular bank section a so-called gate and a magnet for operating it. The gate and associated magnet at the first regular bank section is typical of the others and V will be described briefly.

The magnet is indicated at 15- and includes core 16 and pole pieces 11 and 13 secured to pposite ends of the core. The magnet structure is mounted on the bottom plate 4 of the frame by means of brackets 32 and 13 secured to pole pieces 11 and 13 by screws 35 and 36, respectively, and to flanges 3 and 3 by screws 33 and 34, respectively. The magnet has an armature I33, pivoted on brackets 32 and 13 by means of pivot screws 31 and 33, respectively. Armature I33 has two arms I3I and I32, which extend to the right a short distance beyond the pole pieces 11 and 13, as seen in Fig. 1.

The gate comprises two vertical pieces of angle material 3I and 32, which are pivoted on the upturned ends of arms I3I and I32, respectively,-

by means of pivot screws 33 and 33, said pieces 3| and 32 being held together at the top by a cross member 34 The gate has bearings at the top comprising notches in the ends of strip 63, as shown in Figs. 2 and 6. When magnet 15 is energized, armature I33 is attracted and raises the gate, the vertical side pieces 3| and 32 sliding in the notches in strip 63. When the magnet is released, the gate restores y gravity and comes to restwith projections I36 and I31 engaging flanges 6 and 1 of the top frame plate 3.

The magnet 15 has associated therewith a set of contact springs indicated at I33. The bracket 13 includes a part 33 extending at right angles to part 13 and having 'a downwardly-extending continuation 3I on which the spring I33. are mounted by means of the usual insulators and screws. The springs are actuated by means of a stud I35 of insulating material carried on the arm I34 of armature I33.

Mounted on the cross member 34 at the top of the gate there is aComb-shaped member 36 provided with the spring fingers such as 31.. These fingers are all lightly tensioned to the right against the cross bar 35 which extends across the gate a short distance below cross member 34. Each spring finger 31 is notched at one side, whereby there is formed at the end a lifting arm 33 the upper edge of which is located justto the right of and slightly below the hook 65 on rod 63. The relation between the lifting arms 33 and hooks 65 can be seen clearly from Figs. 1 and 2.

ends thereof are provided for raising the vertical operating bars 80.

As mentioned previously, there is a gate for each regular bank section, or ten gates altogether. From a circuit standpoint the ten gates correspond to the ten trunks, incoming or outgoing, which terminate in the ten bank sections, respectively.

The spring fingers 31 of each gate are all normally ineffective to raise their associated operating bars when the gate is lifted. They are rendered efi'ective selectively by means of a set of ten so-called tens bars which will now be described with reference to Figs. 1, 2, and 3.

One of the tens bars is indicated by the reference numeral III. This bar and nine other similar bars extend lengthwise of the unit in spaced relation just above the upper frame plate 3. The bars are slidably supported at the left in notches in the transverse bar or strip I I2 and are retained therein by means of a strip I I3. At the right hand end the bars are slidably supported in-a notched bar which is similar to bar H2 and are retained in position by a strip I I4. All of the ten bars can be seen in Fig. 3, and also in Fig. 2, from which it will be clear that the bars are equal in number to and are spaced with definite relation to the spring fingers such as 91 on the gates.

The bar III is forced to the right, as seen in Fig. 1, by means of spring H5 and has an offset portion I III at the end which limits its movement in this direction by engagement with the edge of strip H3. The spring H5 is compressed between the angle strip H6 at one end and the bar H3 at the other and bein slightly longer than the distance between these parts it has a curved formation, as seen in Fig. 1. Each of the other nine bars such as bar III is provided with a spring such as spring I I5, as can be seen clearly from Fig. 3.

The bar III is provided with an upwardly-extending projection or cam I2I which is located just to the right of the lower end of spring finger II, as seen in Fig. 1, and with nine similar projections or cams, such as I22 and I23, which are located just to the right of the spring fingers co responding to finger 9'! on the nine other gates, respectively. These ten projections on her III are adapted to bend the ten spring fingers such as 31 to the left and beneath the associated hooks such as 35 when the bar III is moved longitudinally to the left. Each of the other nine tens bars is similarly provided with ten upwardlyextending projections which are adapted to operate the ten spring fingers in the corresponding row.

The tens bars described in the foregoing are selectively actuated by means of ten magnets, such as III, I32, and I30, which are mounted on the top frame plate 3 in a manner similar to the way in which magnets 15 are mounted on the lower frame plate 4.

Magnet I3I, which is the same as the others, includes the usual core I42 and pole pieces I31 and I33, which are secured to brackets I33 and I33 by means of screws I43 and I, respectively. The-two brackets, in turn, are secured to the flanges 3 and 1 or top plate 3 by means of screws I and I43, respectively. The magnet I3I has an armature 23I, which is pivoted on brackets I33 and I33 by means of pivot screws I" and I, respectively. The armature 23I has an upwardly extending arm I40, for operating aset of contact springs which has been .omittedin orderto avoid obscuring the parts beneath it.

and a downwardly-extending part I33 which merges into a transverse member 25 i, Fig. 1. formed integrally therewith and spanning all the tens bars such as I I I.

When the magnet I3I is energized the armature 23I is attracted and the member ZSI is moved to the left, coming into engagement with a vertical member 2 riveted to the tens bar III and moving bar III to the left. Only bar III has a vertical member such as 2 associated with member 25I and consequently only the tens bar III is actuated by the energization of magnet I3I. The next tens bar has a vertical member 242 which is associated with the transverse member 252 actuated by the armature 232 of magnet I32, and each succeeding tens bar has a similar vertical member, which is, however, in each case disposed one position to the right of the corresponding vertical member on the preceding tens bar. Thus the armature of the tenth or last magnet I30, seen in Fig. 3, has a transverse member which cooperates with the vertical member 240 on the tenth or last tens bar. From the foregoing it will be understood that the ten vertical members, such as 2, 242, and 2", are positioned on a diagonal line, viewing the unit from the top, which extends from the first member 2 on the first tens bar to the last member 240 on the tenth tens bar. Each armature such as 23I is provided with a transverse member such as 25| spanning all the tens bars merely for the sake of uniformity, that is, to enable all the armatures to be made alike.

The bracket I33 includes -a portion 233 which extends parallel to magnet-I3I for a short distance and which has a vertical extension 234 on which a set of contact springs are mounted in conventional manner. These springs are shown in the case of magnet I32, and are indicated by reference character 236. They are operated by the insulating stud HI on arm I40 of armature 232. Each tens magnet is provided with a similar set of contact springs.

The operation of any tens bar results in the operation of mechanism shown in Figs. 1 and 3 for closing all the contacts in the corresponding vertical row in the special bank section hereinbefore described. The contacts in the row corresponding to tens bar I II and including contact spring 54 are operated by means of a vertical operating bar comprising a rod H3 and a cylindrical body H9 molded thereon with projections extending underneath the contact springs such as 54. This operating bar may be similar to bar Bil-6i, Fig. 2, although only onethird of the side projections are used. The bar II8-II9 is supported in bearings the same as bar 6Ii- 6I and the other bars in the same transverse row. The upper end of rod H8 is bent at right angles to the main portion of the rod and the short horizontal section thus formed carries -a roller I I! which rests on the spring I I5. When the tens bar III is actuated, that is, moved to the left, the spring II5 assumes a greater curvature and the roller II! is raised, carrying with it the operating bar II8-II8. Thus all the contact springs such as 54 in the vertical row.are operated.

There are nine other operating bars similar to bar II8--I I3, all located in the same transverse row. The rollers such as I" for' operating these bars can be seen in Fig. 3.

It will be recalled now that each of the regular bank sections includes ten intermediate link circuits extending transvesely oi the unit. The

- associated contact springs.

lower link circuit of the first section comprises the conducting strips 66, 26, and I6, and terminates in the contact springs 66, 66, and I1, these three springs constituting a set. There are nine There are ten operating members for the ten I sets of contacts above referred to, each member comprising a recessed block of insulating material having projections thereon for operating the Fig. 2 shows the first and second blocks I66 and I6 I, and the last block I62. Block I66 will be described in detail. It

may be molded in one piece of some plastic compound and has three projections I66,'I61, and I66 which extend beneath the three contact springs I12, I16, and I16, respectively, of the associated set. These projections rest, respectively, on the three contact members, such as I16 and I11, which are immediately beneath them.

contact members such as I16. The other blocks,

such as I6I and I62, are supported the same way. It will be understood that when the gate ,is raised the part 66 thereof slides in the slots I66 of the several blocks and these blocks remain stationary. Means is provided, however, for moving a selected one of the blocks along with the' gate when it is raised. The selecting means includes a set of ten soecalled units bars which will now be described.

Seven of the ten units bars-are shown in Fig. 1.

The v first two bars are indicated at I 6 I and I62, and the last or tenth bar at I66. For the purpose of supporting these bars there are provided two vertical strips I61 and I66 which in turn are supported on angle pieces I66 and I66, the latter being secured to the flanges 1 and 6 on the top and bottom plates of the frame. The angle piece I66 not only supports the strip I61, but also supportsthe units magnets, as will be explained presently. The strips I61 and I66 are slotted on the side toward the unit and the slots are deep enough to extend some distance beyond the edges of angle pieces I66 and I66, thus forming rectangular slots for receiving the bars, such as I8l, I82, and I66, as shown in Fig. 2. The bars fit loosely and aremovable longitudinally to the left, as seen in Figs. 1 and 3. Each bar has a series of ten projections, such as I66, I66, and

I86, which cooperate with spring fingers on the gates for operating: the blocks such as I66.

The particular block I66 is actuatedby means of a spring finger I66, shown in Figs. 2 and 8. At its upper end the spring finger I66 is attached to the angle iece 6| of the gate for the first section. From its point of attachment to the gate the main body of the finger e'xtends angularly downward until a point outside the'block I66 is reached after which it extendsvertically down- On the side opposite the projections I66I66, the block ward and terminates in anangularly d sposed lifting arm I66, which extends to the right, as, seen in Fig. 2. Just abovethe lifting 'arm I66 cured to the armature 262.

and in alignment with the projection I66 on bar I6I there is a projection or arm I66, which extends through opening I66, Fig. 1, in the gate. The parts I66 and I66 are formed integrally with the spring finger I66, which may be punched from a sheet'of suitable material and bent to the shape shown. a

When the units bar III is moved longitudinally to the left, the projections I66, I66, etc., engage the projections I66, I66, etc. on the upper spring fingers of all the gates and move them into operative relation to the associated blocks such as I66. Th projection I66, for example, engages projection'166 and bends spring finger I66 far enough so that the lifting arm I66 enters the recess I16 of the block. Now if the gate 6I-62 is raised, the angularly disposed lifting arm I66 will engage the-surface I1 I. defining the upper side of the recess and will. raise the block along with the gate, thereby pressing the contact springs I12. I16. and I16 into engagement with their associated contact members such as I16.

I6I and I 62, remain unoperated.

The ten units bars such as I6I are selectively operated by means of a set of ten ma nets which are mounted at the left hand end of the unit on the vertical angle piece I66. The magnet 2 I I, associated withv the first tens bar I6I, comprises the usual core and a heel piece 26I, the latter being secured to the angle piece by means of screws 266 and 2I6. The armature 262 has a knif edge pivot on the end of the heel piece 26I, and is pro.- vided with an extension 266 the end of which engages a notch in the end of bar I6I. It will be seen that when magnet 2 is energized, the armature 262 will be attracted and, bar I6I will be moved longitudinally to the left by means of the armature extension 266..

Magnet 2| I also operates a set or contact springs by means of the insulating pin 266 se- These contact springs are mounted on a bracket which forms part of heel piece 26I" and comprises a part 266 bent at right angles to the main body of the heel piece and a part 266 which is bent at right angles to part 266 and which is parallel to the heel piece. The springs are secured to the part 266 by means of the usual insulators and screws. A spring 261 is inserted next to 266 and serves to retain the armature 262 in position.

As shown clearly in Fig. 1, each of the other units bars such as I62 has associatedwith it an operating magnet such as 2I2 which is similar magnet 2| I. 7

It should be stated that the sets of contactsprings which are shown associated with the gate magnets, tens magnets, and units ma nets are to be considered merely as indicating that each of these magnets may have and operate a set of contact springs in 'addition to performing its other function. The exact spring combination used in any case will depend on the switching stage at which the unit is used and may vary even at each stage.

The mechanical details of establishing a connection by means of the described switching unit can perhaps be bestunderstood by reference to Fig.9, which shows in perspective a part of the The other blocks. such as III, which are multipled to the other similar sets of contact members in the same vertical row, as previously described. In order to connect line I I to the first trunk line, the tens bar III and the units bar I8I are actuated, followed by lifting the gate 9|.

When tens bar I I I is moved to the left, its projection III engages the end of spring finger l1 and bends the spring far enough so that lifting arm 8| passes beneath the book 85 on vertical opm crating bar ill-4|. When units bar Iii is moved to the left, the projection Ill thereon engages arm I" on spring finger I63 and bends the latter far enough so that lifting arm I passes underneath the edge "I of the recess in block Ilil. Now when the gate II starts to rise, lifting arm it engages the hook I and slides along the hook a short distance until'the arm engages the vertical portion of rod 80. The slight additional bending of spring finger 01 which is involved in this operation moves arm 9! away from projection III. At the same time the angularlly disposed lifting arm I engages the inclined surface "I on block I" and slides along said surface until the lower end of spring finger it! engages the angle piece ii of the gate, thus moving arm I" away from projection I83. Further movement of the gate now results in the raising of operating bar ill-4i by the lifting arm 08 and the raising of block I" by the lifting arm I".

The operating bar CHI, when raised as described in the foregoing, connects the ten lines terminating in the first vertical row of line bars to the ten intermediate link circuits in the first bank section, and more in particular it connects the line II to the uppermost or first link circuit by pressing contact springs I", I", and I into engagement with bars in, I", and III, respectively. The first link circuit terminates in contact springs I12, Ill, and I", which are pressed into engagement with contact members I15, I18, and III, respectively, by the block I80. Thus the line and trunk are connected.

The connection is maintained by the gate 9|, which remains in operated position. The tens bar III and the units bar ifliare released as soon as the gate has operated. The spring finger O1 is retained In operative relation to bar 5Il--6I by the hook 85, and likewise the spring finger III is retained by the inclined surface III on. block I80. when the gate is restored, the operating bar 806I and the block I are positively restored by the tension in the operated contact springs, such as m and I". On complete restoration of the gate, the lifting arms 98 and I64 drop below hook 65 and surface "I, respectively, and the spring fingers 91 and I6! arepermitted to restore.

As manyas ten connections may be in existence simultaneously; that is, all ten of the trunks associated with the ten bank sections may be in use at the same time. The establishment of all these connections is controlled by the tens and units bars, which are common to the ten gates. Further details of the way in which connections are established, dealing more particularly with the circuits involved, will be found in my Patent No. 2,307,757, previously referred to, which contains a description of the complete telephone system and its operation.

pointed out in the appended claims.

I claim:

1. In a switching mechanism, a group of bars constituting line or trunk terminals, said group being divided into sub-groups arranged in parallel planes, a plurality of intermediate links associated with each sub-group of bars, each link comprising a continuous metal strip extending across the bars of the associated sub-group and having an integrally formed contact finger at the point where it crosses each bar, each strip having also an additional integrally formed contact finger at one end, said links being divided into subgroups located in parallel planes and each subgroup including links associated with different sub-groups of bars, a group of multiple connected trunk contacts associated with the additional contact fingers of each sub-group of links, means for simultaneously actuating the proper contact fingers to connect the links of any sub-group to corresponding individual bars of all the subgroups of bars, and means for individually operating said additional contact fingers to connect any link in the connected sub-group to its associated trunk contact independentof the remaining links in such sub-group.

2. In a switching mechanism, a contact bank comprising a plurality of sections, contact bars extending through all said sections and arranged in groups occupying superimposed parallel planes, a plurality of contacts individual to each section and located in the planes of said bars, a group of continuous contact strips in each section errtending across the bars of said groups, respectively, each strip having an integrally formed contact finger for each bar it crosses and an additional integrally formed contact finger for the contact which is in the plane of the bars, operating means individual to each section for actuating said contact fingers, and means comprising selecting bars common to all the sections for selecting contact fingers to be operated.

3. In a switching mechanism, sets of contacts arranged in superimposed horizontal rows, a plurality of vertical operating bars common to said rows and equal in number to the number of contact sets in each row, a contact set at the end of. each row, individual operating members for said last mentioned contact .sets, means for selecting an operating bar and one of said oper ating members, and a common means for actuating the'selected bar and member.

4. In a switching mechanism, a plurality of bank sections arranged in parallel planes, continuous contact strips common to all said sections, continuous contact strips individual to each section, each said individual contact strip extending successively across a plurality of said common contact strips, sets of contacts in each section associated with said last mentioned strips only, a group of operating bars individual to each section for effecting connection between the strips individual to the section and the common strips, operating members for the said contact sets at each section, a set of bars common to all sections for selecting operating bars, a second set of bars common to all sections for selecting operating members, and means for actuating a select ed operating bar and operating member at any desired section.

5. In a switching mechanism, a plurality of bank sections including a special bank section, each section including sets of. contacts, contact operating bars in each section, selecting bars, means whereby each selecting bar when actuated selects corresponding operating bars for actuation in all said sections except said special section, means whereby each selecting bar when actuated also actuates the operating bar in the special section which corresponds to the operating bars selected in the other sections, and means for actuating any selected operating bar.

6. In a switching mechanism, two banks of contacts, two operating bars for actuating contacts in said banks, respectively, a selecting bar, means responsive to the operation of said selecting bar for selecting one of said operating bars for actuation and for simultaneously actuating the other operating bar, and means for actuating the selected operating bar.

7. In a switching mechanism, a row of longitudinally movable contact operating bars, a common member movable inthe same' direction as said bars, said member including a number of flexible fingers equal in number to the number of operating bars, a plurality of selecting bars, each adapted to bend one of said fingers into operative relation to the corresponding operating'bar, means for actuating any selecting bar, and means for moving said common member to cause the finger which has been flexed by, the

selecting bar to engage and move the associated operating bar.

8. In a cross bar switch, a longitudinally movable group selecting bar, a bow-shaped spring arranged to oppose movement of said bar, said spring being compressed lengthwise between one end of said bar and a fixed support, a connecting bar operated by the increase in the curvature of said spring when said selecting bar is operated,

and means connecting the central portion of said spring with said connecting bar to operate the same as set forth. I

9. In a cross bar switch, a first set of bars for actuating line and test contacts, a second set of bars for actuating test contacts only, a third set of bars for selecting bars of the first set for actu-,

of said selecting bar for operating the first contact actuating bar, an operating device for the second contact actuating bar moved into operative relation therewith by operation of said selecting bar, and meaiiis for operating said device subsequent to operati'on of said selecting bar.

11. In across bar switch, two longitudinally movable operating bars each adapted to close a plurality of sets of contacts, two devices for actuating said bars, respectively, the second of said devices being normally inoperative to actuate its associated, operating bar, means including a longitudinally movable selecting bar for operating the first device to cause the same to actuatethe associated operating bar and for simultaneously rendering the second device. operative, and independent means ior operating said second device to cause the same to actuate its associated operating bar.

12. In a cross bar switch, two contact actuating bars, individual means for operating each said bar, and a selecting bar effective when operated to prepare for operation the individual means associated with one of said contact actuating bars and to operate the individual means associated of contact 'sets, each set comprising line contacts and a test contact, a plurality of groups of test contacts corresponding, respectively, to said groups of contact sets, a first set of bars for actuating the groups of contact sets, respectively, a second set of correspondingbars for actuating said groups of test contacts,-respectiveLv, a third set of bars, and means responsive to the operation of any bar in said third set for selecting a bar of the first set and for operating the corresponding bar of the second set.

14. In a cross bar switch, a group of longitudinally movable selecting bars arranged parallel to each other in spaced relation, a group of individual operatingmagnets for said bars; said magnets being arranged in a row which extends above and parallel to said bars, and actuating members for the bars operated by said magnets and spaced apart along the group in accordance with the location of said magnets.

15. In a cross bar switch, a row of vertical operating bars each adapted to close a plurality of sets of contacts, a common actuating device for said bars comprising vertical side members at opposite ends of said row and a horizontal cross member connecting said side members at the top, a magnet having an armature connected to said side members at the lower end thereof and adapted to raise said device, individual members for lifting said bars supported on the said cross member of said device, and selecting means for rendering any one of said individual members eifective to lift the associated bar upon the raising of said device by said magnet.

16. In a cross bar switch, a pluraity of vertical operating bars disposed parallel to each other in a row, each bar having means forclosing a plurality of sets of contacts, a corresponding plurality of lifting devices arranged in a row at the upper ends of said operating bars, a plurality of with the associated operating'bar, and means for moving all said lifting devices upward in the plane of said operating bars and thereby cause a lifting device which has been moved by a selecting bar to raise the associated operating bar.

1'7. In a cross bar switch, a plurality of vertical longitudinally movable operating bars disposed parallel to each other in a row, each bar having means for closing a plurality of contact sets and terminating in a hook at its upper end, a comblike member extending above and parallel to said row of bars and having flexible depending tongues corresponding to said bars, respectively, means comprising selecting bars for flexing any one of said tongues into operative relation with-thehook on the associated operating bar, and means for moving said comb-like member vertically upward to cause the flexed tongue to actuate its associated operating bar by engaging the terminating hook thereof.

18. In a cross bar switch, a plurality tudinally movable operating bars disposed parallel to each other in a row, each bar. having means for closing a plurality of sets of contacts, a row of normally ineffective individual actuating members for said bars, means including selecting bars for independently moving any actuating member into operative relation with its associated operating bar to select such bar for actuation, and means for moving all said actuating memof longiatlng bar is. actuated.

19. In a cross bar switch, the combination with a plurality of rigid and movable contact members arranged alternately in a row, of an operating bar for said movable contact members comprising a metallic rod extending parallel to said-row and having a continuous molded body formed thereon including projections extending laterally into said row in operative relation to said movable contact members, and means for producing a longitudinal movement of said bar to cause said projections to move said movable contact members into engagement with the adjacent fixed contact members, respectively.

20. In a cross bar switch, a plurality of rigid and flexible contact members arranged alternately in a row, said contact members constituting groups of contact sets, a plurality of longitudinally movable contact actuating members arranged in spaced relation end to end along said row, there being one such actuating member to each group of contact sets, a common longitudinally movable operating member extending parallel to said row and provided with individual devices ior lifting said actuating members, and means comprising selecting bars for rendering any one of said individual devices operative to lift the associated actuating member responsive to movement of said common operating member.

21. In a cross bar switch, a plurality of fixed and movable contacts arranged alternately in a vertical row, a molded block having a vertical groove in one side and a plurality of projections on the other side extending into said row beneath the movable contacts, one or more of said projections resting on fixed contacts to support the block, a member slidable vertically in said groove, and selectively controlled means on said member for lifting said block to actuate said movable contacts.

22. In a cross bar switch, a plurality of builtup bank sections spaced apart in parallel planes, each bank section comprising a plurality of strips of insulating material clamped together in supperimposed relation, a plurality of superimposed spaced groups of rigid metallic bars extending through all said bank sections, the bars of each group being supported at each section between adjacent insulating strips, a plurality of flexible metallic strips extending parallel to the insulating strips in each bank section and crossing said groups of bars, respectively, each strip being clamped between two adjacent insulating strips, and a plurality of integrally formed contact finers projecting from the edge of each said flexible strip in operative relation to the bars of the ass ciated group.

23. In a cross bar'switch, a plurality of strips of insulating material extending parallel to each other in spaced relation, a plurality of flexible metallic strips superimposed on said insulating strips, respectively, each strip having integrally formed spaced contact fingers projecting from one edge thereof, a second plurality of insulating strips superimposed on said flexible strips, respectively, the strips of said second plurality having transverse notches in their upper surfaces which are in alignment with said contact fingers, a plurality of rigid metallic bars arrangedperpendicular to all said strips and resting in said notches, a third plurality of insulating strips superimposed on the said second plurality and resting on said bars, all said parts constituting one bank layer, a plurality of similar layers subers simultaneously, whereby the selected operperimposed on said first layer, and means for clamping said layers together.

24. In a cross bar switch, a plurality of parallel bars arranged in superimposed groups, a plurality of flexible metal strips, one for each group of bars, each strip extending across the bars of the associated group and having an integrally formed flexible contact finger at the point where it crosses each bar, the contact fingers of each strip extending at right angles thereto and parallel to the bars of the associated group, means for supporting said bars and strips in fixed relation to each other, and means for simultaneously flexing a contact finger of each strip into engagement with the associated bar.

25. In a cross bar switch, a plurality of contact sets arranged in equal groups, a second plurality of contact sets equal in number to the number of contact sets in one of said groups, continuous conducting strips having integrally formed contacts and connecting each contact set of said second plurality with a contact set in each of said groups, the said integrally formed contacts constituting contacts of the contact sets connected, means including selecting bars for se-- lecting one of said groups of contact sets and an individual* contact set of said second plurality, and means including an electromagnet common to all said contact sets for simultaneously closing all the contact sets of the selected group and the selected individual contact set.

26. In a cross bar switch, a plurality of pairs of contacts, each pair including a fixed contact and a movable contact, said pairs being arranged in equal groups, a second plurality of pairs of fixed and movable contacts equal in number to the number of pairs in one of said groups and the movable contact of each pair being formed integrally with corresponding movable contacts in each of said groups, means including selecting bars for selecting one of said groups and an individual contact pair of the second plurality, and means including an electromagnet common to all said contact pairs for simultaneously moving the movable contacts of all the selected pairs into engagement with, their associated fixed contacts.

27. In a cross bar switch, a plurality of trunking sections, multiple connected trunk contacts at each section, continuous conducting bars common to all trunking sections and arranged in groups,

continuous conducting strips individual to said trunking sections, each strip intersecting one bar oi! each of said groups and having integrally formed contact fingers for cooperation therewith, also a similar contact finger for cooperation with one of said trunk contacts, and means at each trunking section for operating the proper contact fingers to connect the individual strips at such section with the bars of one of said groups,

respectively, and to simultaneously connect one of the connected strips to the associated trunk contact, said means including individual separately operable devices for connecting said strips and trunk contacts, whereby any one of the connected strips may be connected to the associated trunk contact by operation of its individual device while the'other strips remain disconnected from their associated trunk contacts.

28. In a cross-bar switch, a plurality of groups of longitudinally movable operating bars, each group comprising a plurality of such bars arranged side by side and,parallel to each other in a row, a plurality of sets of contacts arranged for operation by each bar responsive to longitudinal movement thereof, said contact sets ineluding continuous contact bars each common to a plurality of contact'sets which are associated with operating bars in difierent rows, a row of individual actuating members for each row of operating bars, selecting bars common to said rows of actuating members, each selecting bar having means for effecting operative relation between one actuating member in each row and its associated operating bar, and means for moving all the actuating members in any row to the exclusion of those in the other rows, whereby a particular selected operating bar is I actuated.

29. In a cross-bar switch, a plurality of bank sections each including a plurality of continuous conducting strips in superimposed spaced relation, means in each bank section for establishing connections simultaneously to all the strips in such section at any one of a plurality of points along the length thereof, the said strips in each section being arranged in sets, each set including a plurality of strips, a row of individual devices at the end of each bank section for establishing connections to the said sets of strips, respectively, in such bank section, a plurality of selecting bars common to all said rows of devices, each selecting bar when operated being effective to prepare for operation one device in each said row, a com- 4 mon operating mechanism for the devices'in each row, and means for operating any one of said operating mechanisms to actuate any particular one of the devices prepared for operation by an operated selecting bar.

30. A switch structure of box-like conforms; tion, comprising transverse contact bank sections spaced apart lengthwise of the structure, continuous contact bars extending through all said bank sections, said contact bars being divided into groups, continuous contact strips in each bank section common to all the groups of contact .bars, said contact strips constituting connecting links, group selecting bars common to said sections, each selecting bar being operative to select a. group of contact bars for connection to thelinks at all sections, contacts at each section individual to the links at such section, respectively, link selecting bars common to all said sections, each link selecting bar being operative to select a link at each section for connection to its associated individual contact, means for operating any group selecting bar and any link selecting bar, connect ing means at each section'for closing the connections at such section selected by the operated selecting bars, and means for operating the connecting means at any section independent of the connecting means at the other sections.

31. A switch structure of box-like conformation, comprising transverse contact bank sections spaced apart lengthwise of the structure, continuous contact bars extending through all said bank sections, said contact bars being divided into groups, tens selecting bars common to said sections for selecting groups of contact bars,

means in each section for extending connections simultaneously to a selected group of contact bars, units selecting bars common to said sections for selecting an individual contact bar in the selected group, means in each section for extending a connection to such selected contact bar, said last mentioned connection including in series therewith one of said first mentioned'connections, and means for operating the said connecting means in any section independent of the connecting means in the other sections.

32. In a cross-bar switch, a plurality of regular bank sections each comprising a plurality of con tinuous strips having integrally formed contact fingers projecting from the edge thereof, the strips of each section being arranged one above the other in spaced relation, a special bank section comprising a lesser number of strips which correspond, respectively, to certain of the strips in said first mentioned sections, continuous contact bars extending through all said bank sections in operative relation to the contact fingers in said regular bank sections, certain of said bars also being in operative relation to the contact fingers in said special bank section, operating bars for each bank section, each bar adapted to move a plurality of contact fingers into engagement with the corresponding contact bars, tens magnets for selecting operating bars in said regular bank sections for operation, means responsive to the energization of any tens magnet for actuating an operating bar in said special bank section and for selecting an operating bar in each regular bank section, and means for subsequently operating the selected operating bar in any regular bank section.

33. In a cross-bar switch, a plurality of groups of continuous contact bars, each groupof bars comprising a plurality of sets of bars, and each set including two line bars and a test bar, a plurality of regular bank sections, each comprising continuous strips extending across the line and test bars of all said groups, a special bank section comprising continuous strips extending across the test bars of said groups, operating bars in each regular bank section each adapted to effect engagement between the strips at the associated bank section and a group of contact bars, operating bars at said special bank section each adapted to effect engagement between the strips thereat and the test bars of a group of contact bars, tens magnetsior' selecting operating bars in said regular bank sections, means responsiveto the energization of any tens magnet for actuating an operating bar in said special bank section and for selecting for operation an; operating bar in each regular bank section, and means for actuating the selected operating bar in any regular -bank section to the exclusion of the selected bars sections. 

